The gut-brain connection: triggering of brain autoimmune disease by commensal gut bacteria.

In a transgenic model of spontaneous experimental autoimmune encephalomyelitis, autoimmune attack against the CNS requires the presence of an intact commensal gut flora. Extending this observation to human autoimmune disease, such as multiple sclerosis, we postulate that the pathogenic reaction requires the coincidence of at least three factors: a permissive genetic disposition, a pro-inflammatory intestinal microbial profile, and the accumulation of autoreactive T cells in the gut-associated lymphatic tissue. This concept may offer new approaches to diagnostic markers and non-invasive therapies.